The primary goal of this research is to examine the role of noradrenergic and dopaminergic systems in brain in the maintenance of self-stimulation and in: the action of drugs which affect this behavioral response. In work in which stimulation electrodes were placed in the lateral hypothalamus, it has been found that pharmacological treatments which reduced brain dopamine attennated self-stimulation responding, while those treatments which reduced brain norepinephrine did not affect responding. Since these experiments suggested that dopaminergic fibers are involved in the maintenance of this task, animals were studied have electrodes implanted in an area of brain not known to contain dopaminrgic fibers in the locus coeruleus. When these animals were treated with 6-hydroxydopamine, no chronic deficits in self-stimulation were observed. However, alpha-methyltyrosine reduced self-stimulation responding when adminstered to rats in which brain dopaminergic fibers were destroyed. Neither destruction of noradrenergic fibers nor further treatment with a dopamine-Beta-hydroxylase inhibitor altered responding from locus coeruleus electrodes. These findings suggest that dopaminergic fibers play an important role in the maintenance of this behavior even from a brain area that has no known dopaminergic innervation. BIBLIOGRAPHIC REFERENCES: Breese, G.R. and Cooper, B.R. Relationship of dopamine neural systems to the maintenace of self-stimulation. In Neurotransmitter Balances Regulation Behavior edited and published by E.F. Domino and J.M. Davis. Ann Arbor, Mich. pp. 37-56, 1975.. Cooper, B.R. and Breese, G.R. A role for dopamine in the psychopharmacology of electrical self-stimulation. In Aminergic Hypotheses of Behavior: Relatity or Cliche? Edited by B.K. Bernard. NIDA, Rockville, Maryland. pp. 63-70, 1975.